Veteran republican Ms Bernadette McAliskey was arrested at Chicago Airport and deported two hours after her arrival in the US for being regarded as a "potential security threat".
The 55-year-old campaigner said she was told she was ineligible for entry to the United States "on the basis of a review of my status which designated me as a potential threat to the security of the US".
When immigration officials checked her file on their computer it showed no change in her status, she maintains. Officials told her however, they could not override a fax from "immigration in Dublin that I was on this flight, that I was ineligible for admission and that I had successfully evaded immigration".
A US embassy spokeswoman said, however, that the embassy did not comment on individual consular cases, but they were unaware of the incident.
The campaigner, who first came to prominence as the youngest MP elected to the House of Commons over 30 years ago, claimed that the information on which she was denied access was false and that she was excluded from the US "merely on the whim of a person in Dublin".
Ms McAliskey, who was questioned, photographed and finger-printed, said she would make a formal complaint to the US State Department about her treatment and would write to the Department of Foreign Affairs about what authority US immigration had on Irish soil.
If she could not have redress through them she would go to the UN "because the US can't just go around bullying people", and denying their basic human rights.
Speaking yesterday from her Co Tyrone home, Ms McAliskey said she was travelling to the US for "the first time in my life for no purpose other than to have a holiday". She said she was a regular traveller to the US. Ms McAliskey travelled with her daughter Deirdre on a five-day holiday package to New York travelling via Chicago.
The former Bernadette Devlin said she had served six months for riotous behaviour in 1969 but her ineligibility to travel to the US expired in 1989, and this was on computer at US immigration. New visa-waiver forms ask about convictions with an "aggregate total of two years".
She cleared immigration in Dublin, filling in a visa-waiverform and when she arrived in Chicago, her name was called out on the PA system.
When she identified herself she was "surrounded" by four immigration officials, and maintains she was threatened with handcuffing and told that officials had authority to shoot.
Ms McAliskey said that her arrest and deportation "is not because I am who I am. I could just as easly have been Mrs Smith. They had no idea who I was".
